Contrasting student and also scientific views

Student daily experiences

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Many young students will certainly have had actually memorable however often confusing experiences with magnets and magnetic materials. Magnetic products are consistently encountered around the home, often holding little objects ~ above the kitchen fridge or keeping cupboards and also fridge doors closed. Numerous children’s playthings employ weak magnets to ‘stick’ materials together (e.g. Wooden train carriages) or are provided in an easy children’s building and construction toys to enable them to easily assemble more complex structures without the require for confusing adhesives or challenging connections. Toys really rarely make use of magnetic repulsion.

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Many younger students space yet to kind strong see or in plenty of cases any views at all around how magnets communicate with matter or each other. They do not watch the have to discriminate in between magnetic forces and electrostatic pressures (or gravity). To them, these often show up to be typical experiences that the same invisible non call force, usually just attraction. For example, a balloon ‘rubbed’ v a towel resulting in that is attraction to another object is frequently described incorrectly by young students (and also some adults) as having been ‘magnetised’ in some way.

Students’ confusion around non call forces is explored in the emphasis idea Electrostatics – Level 4.

It is well created that enlarge students organize a variety of views around magnetism the vary significantly in your sophistication, varying from magnetic models with bordering ‘clouds’ of activity to ideas around ‘electric rays’ and also ‘fields’. However, numerous younger students simply associate magnetism v a ‘pulling force’.  Understandably your naive model has no predictive or explanatory power and also they frequently do not perceive the need to do an ext than identify and also label the attractive or the less regular repelling behaviour as magnetic.

Research:  Erikson (1994), Borges & Gilbert (1998), Haupt (2006), van Hook & Huziak-Clarke (2007), Ashbrook (2005), Hickey & Schibeci (1999), Maloney, O’Kuma, Heieggelke & van Heuvelen (2001)

Scientific view

We frequently encounter magnetic areas in our everyday experiences (e.g. The earth magnetic field and magnetic fields developed by electrical current). However, the vast bulk of the magnetic fields around us are just too weak to cause any type of observed results or remain ‘removed from us’ because they room utilised in more facility machines like electrical motors and computer hard drives.

Magnetic attraction and also repulsion is just one of three fundamental non contact forces in nature. The various other two forces are electrostatic and gravitational (see the emphasis idea forces without contact at level 4, Electrostatics – Level 4 and also Gravity - Level 6).

The vast majority of magnets we encounter (e.g. Refrigerator magnets, door catches and magnetic toys) are produced from products which room ferrom​agnetic. These products are based on mixtures the iron, nickel or cobalt together these are the only three recognized ferromagnetic elements. Stronger commercial magnets deserve to be made v these and the addition of an ext expensive rare planet elements.

The atom in ferromagnetic products are different because they can behave like small magnets. Typically the magnetic field approximately each atom points in a arbitrarily direction bring about them cancelling each various other out (see number 1). However if the neighboring magnetic ar is solid enough, that is feasible for them come align for this reason they each add to develop a more powerful magnetic ar in the product (see figure 2). They can also remain aligned once the surrounding field is removed creating a long-term magnet.

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Typical magnets found roughly the residence or used in etc ‘pick ups’ or fish tank glass cleaners are built with ferromagnetic materials and also can develop permanent magnetic areas with intensities as much as 3000 times the of the earth magnetic field.Ferromagnetic materials are usually an extremely brittle and will easily chip or fracture if to reduce or enabled to slam together. Castle will likewise lose their permanent magnetic nature if heated strongly. All of these actions reason the individual atoms to shed their alignment.The magnetic areas surrounding every magnets are claimed to have two poles, referred to as North and South. These names originate native the observation that magnets will certainly align in the direction that the earth weak magnetic field if permitted to swing openly i.e. Direction detect magnetic compasses depend on this principle to operate. The ‘north pole’ that a magnet bring away this name since it always points in the direction of the earth’s north geographical magnetic pole.Similar magnetic poles repel and also unlike magnetic poles lure each other. 

Critical teaching ideas

Magnetic pressures are non contact forces; they pull or press on objects without poignant them.Magnets are just attracted come a couple of ‘magnetic’ metals and also not every matter.Magnets room attracted to and also repel various other magnets.

At criter up to and including Level 3, the is suitable to encourage students come observe and also explore magnetic phenomena v play. Students have to be helped to develop basic understandings the the it was observed attraction of magnets to some ‘special’ steels (not every metals) and also their attraction and also repulsion to other magnets. Students have to be urged to discriminate between magnetic forces, electrostatic and also gravitational forces as being various to each other yet examples of pressures that can act there is no physical call taking place i.e. Examples of non call forces.

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Explore the relationships in between ideas about magnetism and non call forces in the Concept development Maps –  Electricity and Magnetism.

Teaching activities

Provide an open problem to be discover via pat or through difficulty solving

Provide students v a range of various materials because that them to inspection which ones have actually magnetic properties. This materials could include samples of: paper, plastic, polystyrene, wood, glass, rope, leaves, ceramic, rock, and some objects do of steel or steel. Look come use just metallic objects make from steel or steel so students deserve to see that being composed of a solid metallic material is a usual property.

Provide students v a bag the samples (say 12-15) and have them check the samples with a bar magnet or refrigerator magnet to view which ones room attracted come the magnet.  Ask them to kind the objects into two separate groups: those that show up to be attractive to a magnet and also those which carry out not.

Invite the students to market suggestions of common features the the objects in the group that to be attracted come the magnet. Is it their colour, weight or the problem they space made of that might make the difference? have actually students suggest and test their principles to identify feasible common properties.

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Next, ask student if every objects make of metallic materials are magnetic. Have any students had experiences which imply otherwise? Now provide students v a variety of objects do from different metals and also ask castle to sort the objects right into two piles, predicting i m sorry objects will be attractive to a magnet and which will certainly not. Some examples of metals and their sources might be: aluminium cans or foil, brass keys, copper pond or wire, steel screws or nails, zinc flashing or solder, stole bolts or nails, lead fishing sinkers and nickel welding rods.  

After sorting the objects students have the right to then check them to see if they have correctly guess which materials are magnetic.

The intention below is to encourage students to test various materials and through examination recognise that just a couple of metals have magnetic properties. Crucial point to be made is that in our day-to-day experience most metals show up to be magnetic since the most widely used metal is stole containing iron.

Open up conversation via a shared experience

Most college student are acquainted with magnets ‘attracting’ magnetic products or being attracted to some metallic surface such as fridges and white boards, yet they are much less acquainted with magnetic forces that repel every other. This is do more daunting for students to explore since they must have at least two magnets of similar strength and many of the familiar advertising refrigerator magnets provided for basic investigations are weak and also constructed in a way that they have no identifiable magnetic poles.

Try to obtain a variety of ‘fish tank’ glass clean magnets i beg your pardon are supplied in bag or ‘cow magnets’ accessible from some farming produce stores. The surfaces of these magnets room well protected and also will mitigate the risk of students accidentally pinching fingers or the magnets shedding fragments if tackled roughly.

Ask the students to inspection what they must do to make the magnets attract and repel every other. Have actually them identify various ends of each magnet through identifying stickers. Exactly how well deserve to the students guess what will happen when the magnets are carried near to each other?

Now encourage students to use masking ice to deal with one magnet ~ above the roof of a toy car. Use the hand hosted magnet to push the vehicle along without emotional it or to entice the car towards it by transforming its orientation. Deserve to students predict if the magnet ~ above the auto will be attracted or repelled by the technique of a new magnet?

The intention below is for students come recognise that magnets deserve to repel and attract every other. At this level it is not thought about important for students to have the ability to recall that prefer poles repel and also unlike poles attract, however to recognise the magnets can repel and also attract without making physical contact and also that their orientation is important.

Open conversation via a mutual experience

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Students can be urged to investigate if magnetic pressures pass through various other non magnetic materials. To capture student interest, ar a magnet (such as a fish tank glass clean magnet) top top a great table. Introduce one more magnet (the other glass cleaning magnet) under the table for this reason the two space strongly attracted.  Position the magnet therefore you deserve to move the magnet under the table through your knee or various other hand. The magnet ~ above the table peak will follow the movement of the magnet below. This mysterious movement of the magnet on the table will certainly impress students yet eventually they will uncover the ‘trick’ that the second magnet under the table.

Have the students certain a magnet come a stand or the optimal of a tiny water bottle utilizing some ‘blue tack’ or adhesive ice cream so that overhangs the side face of the bottle. Next have them settle a document clip come a size of noodle with sufficient length to with from the table top to the magnet. Lastly use some ‘blue tack’ to solve the cotton to the table so the record clip is just brief of reaching the magnet and also appears suspended in mid air through a gap between it and also the magnet.

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Encourage student to inspection if various products will avoid the magnetic force of attraction when they are introduced between the magnet and the document clip. Shot sheets the paper, glass, tile, aluminium foil, copper and zinc sheet. Do any type of of this materials have an result on reduce the magnetic force?

The intention below is because that students to observe that magnetic pressures will continue to be unhindered and can travel v most materials without any type of effect.

Helping students workout some of the ‘scientific’ explanations for themselves

Collect a number of uncoated cable coat hangers and cut and straighten castle into brief lengths which range from 10cm come 20cm long. Distribution a couple of these roughly to students working in pairs or triplets, making sure they are given different sized lengths. Also pass around a number (5 to 8) of little paperclips to each group. Deliberately carry out not pass out any magnets just yet to protect against students bringing lock into call with the cable lengths.

Encourage the college student to investigate if any of the lengths that wire room successful in attracting any type of of the paperclips. If the cable lengths have not make previous call with any type of magnets then they should display no magnetic properties and also not annoy the paperclips.

Now pass the end a permanent magnet to every of the student groups and demonstrate just how you have the right to use one end of the magnet come stroke the wire length consistently in one direction causing it to come to be magnetised. Students can then repeat this through their very own lengths the wire and determine if they have been effective in do a magnet by testing its ability to entice or background up number of paperclips. 

This an approach of magnetisation is constant with the idea of making use of a magnetic ar (from the magnet) to significantly align the direction the the atom acting together tiny magnets in the wire. Share this explanation through students is not recommended.

Have students define what lock did and also discuss exactly how successful they were in make a magnet.

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Collecting evidence and also data for analysis

After students have successfully made one size of wire into a irreversible magnet, collection them the challenge of making the most an effective magnet castle can. They have the right to again test their success by attracting and also lifting as numerous of the paperclips as they can with your wire magnets. Have students from each team record the variety of paperclips your magnet deserve to lift. Encourage students to investigate various properties of the wires the may add to making much better magnets e.g. To compare the variety of times each was stroked, the size of the wires and the approaches used to stroke every wire.